Overview

The compressor controls the pressure ratio (and hence the thermal efficiency) of a gas turbine engine, and the mass flow as well, so it has a dominant influence on the engine's characteristics. For this reason and because it has been one of the most difficult engine components to develop, it has received great emphasis in both research and development. These efforts, which go back to the 1940s, continue unabated. Since fuel costs are a major portion of direct operating costs for commercial aircraft, there is a continuing strong motivation to raise the compression ratio of engines and to improve compressor efficiency. In military engines for multi-mission aircraft, such as air superiority fighters and attack aircraft, the mass flow per unit of frontal area and the weight of the compressor are important factors. The stability of the compression system is an additional major consideration for these military engines, which have to operate under a very wide range of conditions.

To address these complex and difficult requirements, the aircraft engine industry has long conducted a broad and deep research and development program, with some involvement of academics and support from government, primarily the NASA and the Department of Defense. Whereas in the 1970s the design and development of a new compressor involved a good deal of trial and error, the art has now advanced to the point that a new compressor can be designed with some confidence that it will perform well as designed, provided that its design does not differ...